NASA's Cassini spacecraft has provided new images of Saturn's
moons Tethys and Hyperion, showing features not seen
before.
Last
weekend, Cassini flew closer than ever before to each
of them.
Tethys
has a scarred, ancient
surface, an icy landscape with steep cliffs and craters.
A giant
rift called Ithaca
Chasma cuts across the disk of Tethys. Much of the topography in this region, including
that of Ithaca Chasma, has been thoroughly hammered
by impacts. This appearance suggests that the event that created Ithaca Chasma happened very long ago.
A new image
of the Tethys' south polar region shows a region not photographed
during the Voyager era.
Astronomers
described Hyperion
as spongy-looking with dark-floored craters that speckle its surface.
Scientists don't know what the dark material is.
In
addition, the new images suggest the possibility that Hyperion's crater walls
have experienced multiple episodes of landslides. Such "downslope" movement is evident in the filling of
craters with debris and the near elimination of many craters along the steeper
slopes.
Answers to
these questions may help solve the mystery of why this object has evolved
different surface forms from other moons of Saturn, scientists with Space
Science Institute in Boulder, Colorado said in a statement today.
Cassini
flew by Hyperion at a distance of 310 miles (500 kilometers). Hyperion is 163
miles (266 kilometers) wide. It has an irregular shape, and spins in a chaotic
rotation. Much of its interior is empty space; it's like a pile of rubble,
scientists say.
Cassini
was within 930 miles (1,500 kilometers) of Tethys, a
moon that is 665 miles (1,071 kilometers in diameter.
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